Overview
The Leiter International Performance Scale – Third Edition (Leiter-3; Roid, Miller, Pomplun, & Koch, 2013) is an individually-administered, nonverbal measure of intelligence useful for assessing those with cognitive delays, speech or hearing problems, motor impairments, ADHD, traumatic brain injury, or those who do not speak English. It can be administered for persons between 3 and 75 years old. The Leiter-3 includes two groupings of subtests: the Cognitive Scales that measure fluid intelligence and the Attention and Memory Scales. The Attention and Memory Scales were designed to distinguish children with ADHD or other neuropsychological impairments from typical children, as well as to enhance interpretation of the global IQ score by providing valuable diagnostic indicators to help explain scores on the Cognitive Scales. The Leiter-3 emphasizes fluid intelligence, and the global IQ score is not significantly impacted by language skills or by experiences (educational, social, family).
Summary
Age: 3 years to 75+ years
Time to Administer: 20-45 minutes
Method of Administration: Individually administered, norm-referenced nonverbal measure of intelligence
10 subtests in 2 domains, Cognitive Scales (Fluid Intelligence) and Attention and Memory Scales.
Yields standard scores (M = 100, SD = 15) for composites,
scaled scores (M = 10, SD = 3) for subtests, percentile ranks, confidence intervals, and age equivalents. Also yields Growth Scores to indicate small improvements in people with significant cognitive disabilities.
Subscales: Overall Composite Score: Nonverbal IQ
Additional Composite Scores: Nonverbal Memory, Processing Speed
Subtest Scores: Sequential Order; Form Completion; Classification and Analogies; Figure-Ground;
Matching/Repeated Patterns (optional); Forward Memory; Reverse Memory; Attention Sustained; Attention Divided; Nonverbal Stroop
Autism Related Research
None found. Though not focused on the Leiter-3, Tsatsanis et al. (2003) studied concurrent validity and classification accuracy of the Leiter and Leiter-R in low-functioning children with autism (n = 26) and found that correlations between scores on these two scales were high ( r = .87) and difference between mean scores were non significant. However, in 38% of this sample, significant intraindividual discrepancies were found. Overall, the authors concluded that the Leiter-R was useful for children with autism but noted that greater clinical success may be achieved using the original Leiter for very low functioning and severely affected children, particularly young children.
In addition, Grondhuis and Mulick (2013) compared the Leiter-R with the Stanford-Binet Intelligence Scales- Fifth Edition (SB-5) among 47 children with ASD using hospital records. They found that the Leiter-R yielded significantly higher scores than the SB-5, particularly among young children. The authors concluded that these two tests may not be equivalent measures of intellectual functioning in children with ASD and using only one could result in misclassification of intellectual ability. This finding (Leiter-R scores > SB-5 scores) was replicated by Grondhuis et al. (2018) in another sample, also using the SB-5 and the Leiter-R, within a sample of 80 children with ASD and comorbid disruptive behavior disorders who were participants in a randomized clinical trial. Conclusions included that use of both traditional and nonverbal IQ tests might better capture the level of functioning and needed educational supports among children with ASD.